Apparatus for completing plural zone oil and gas wells

ABSTRACT

A tubular receptacle is connected in a string of permanent production liner at a point at which the production tubing for an upper one of two different subsurface producing zones is to be terminated. The interior of the receptacle is coated with Teflon. A first of two longitudinal flow passages in a cylindrical body member is connected at an intermediate point in a string of production tubing for the lower of the two producing zones and such tubing string is run into the well bore to seat the cylindrical body member in the liner receptacle. The cylindrical body member has resilient annular seal means on the exterior thereof for providing a fluidtight seal between the liner string receptacle and the body member. The tubing string for the upper zOne is run into the well bore and seated in the upper end of the second flow passage in the cylindrical body member.

I United States Patent 11 1 3,640,341 Braddick et al. 1 Feb. 8, 1972 541 APPARATUS FOR COMPLETING 3,283,570 11/1966 Hodges 166/1 15 PLURAL ZONE OIL AND GAS WELLS 3,397,745 8/1968 Owens et al. ..l66/57 [72] Inventors: Britt 0. Braddick, Houston; Hiram E. P E es A Le k Lindsey, Jr., Midland; Charles J. 23 ppm McKiearnan, Odessa, all of Tex.

[73] Assignee: Texas Iron Works, Inc., Houston, Tex. [57] ABSTRACT [22] Filed: Nov. 6, 1969 A tubular receptacle is connected in a string of pcrmiuicnt 17 production liner at a point at which the production tubing for [21 1 App! 8746 an upper one of two different subsurface producing zones is to be terminated. The interior of the receptacle is coated with [52] U.S. Cl ..l66/115, 166/189 Teflon. A first of two longitudinal flow passages in a cylindri- [51 1 [I'll- Cl ..E2lb 33/12 cal body member is connected at an intermediate point in a [58] Field Of Search 1 1 15, 57, 189 tring of production tubing for the lower f the two producing zones and such tubing string is run into the well bore to seat 1 1 References the cylindrical body member in the liner receptacle. The cylin drical body member has resilient annular seal means on the UNITED STATES PATENTS exterior thereof for providing a fluidtight seal between the Re26,3 I9 12/ l 967 Tamplen --1 6/1 1 liner string receptacle and the body member. The tubing string 1,400,996 12/1 21 Ch rer--- 166/ l 89 for the upper zOne is run into the well bore and seated in the 2,286,075 6/1942 Evans 156/53 upper end of the second flow passage in the cylindrical body 2,999,543 9/1961 Myers 166/189 memben 3,008,522 11/1961 Fredd et al ..166/115 3,182,726 5/1965 Stone, Jr ..l66/1 15 9 Claims, 2 Drawing Figures mtmw ran 81912 INVENTURS Jade, Hflgdtlw &

/] TTOR/VE YS Richamb Bee 3 M 2 H j APPARATUS FOR COMPLETING PLURAL ZONE OIL AND GAS WELLS CROSS-REFERENCE TO RELATED APPLICATION This invention is an improvement over our copending application Ser. No. 799,657 filed Feb. 17, 1969 for Method and Apparatus for Completing Oil and Gas Wells, now US. Pat. No. 3,531,236.

BACKGROUND OF THE INVENTION This invention relates to apparatus for completing multiple completion oil and gas wells.

Multiple completions are performed in a single oil or gas well for purposes of producing hydrocarbons from two or more different subsurface producing zones located at different depths below the surface of the earth. In order to accomplish this purpose, it is necessary to isolate the different producing zones from one another and to provide multiple strings of production tubing running from the different producing zones to the wellhead equipment located at the surface of the earth. The isolation function is customarily accomplished by setting production packers in the well bore casing or production liner at appropriate points intermediate and above the different producing zones. In order to accommodate the passage of multiple tubing strings, the upper one or ones of these packers is normally of a relatively complex form of construction and the setting of same usually requires a considerable amount of care. In addition, the use of such production packers frequently makes it more difficult to reenter the lower portion of the well bore at a later date for purposes of conducting workover operations and the like.

SUMMARY OF THE INVENTION It is an object of the invention, therefore, to provide new and improved apparatus for completing plural zone oil and gas wells in an improved and simplified manner.

It is another object of the invention to provide new and improved completion apparatus for plural zone oil and gas wells which simplifies later reentry into the lower portion of the well for workover purposes and the like.

In accordance with the invention, apparatus for use in completing oil and gas wells for producing from a plurality of subsurface zones comprises a tubular receptacle member adapted to be permanently connected into a string of permanent production liner. The apparatus further includes a cylindrical body member adapted to be inserted into the receptacle member. Such body member includes a plurality of flow passages extending longitudinally therethrough. The apparatus also includes resilient annular seal means mounted on the exterior of the body member for providing a fluidtight seal between the receptacle member and the body member.

For a better understanding of the present invention, together with other and further objects and features thereof, reference is had to the following description taken in connection with the accompanying drawing, the scope of the invention being pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWING Referring to the drawing:

FIG. I is a cross-sectional view of a portion of an earth borehole showing in place therein a cross-sectional view of well completion apparatus constructed in accordance with a representative embodiment of the invention; and

FIG. 2 is an enlarged cross-sectional view of a portion of the FIG. 1 apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. I, there is shown a section of a borehole I drilled through subsurface earth formations ll. Cemented into place in the borehole I0 is a string of casing 12 which extends from the surface of the earth to a depth somewhat above the producing zones. The cement is indicated at 13. Extending from the lower end of the casing 12 is a string of permanent production liner 14 which extends downwardly to the bottom of the borehole 10. Such production liner 14 is also cemented into place by the cement 13. Connected to the top of the production liner string 14 is a liner hanger 15 for clamping the liner string 14 to the interior wall of the lower joint of the casing string 12. Liner hanger 15 may be of a known cone and slip type construction and may be of either the mechanically or hydraulically operated type.

Two different subsurface producing zones are located adjacent perforated zones 16 and 17 in the liner string I4. The individual perforations in these zones extend through the wall of the liner string 14, the surrounding annulus of cement I3 and into the adjacent earth formation material. These perforations provide flow passages for enabling the formation fluids to flow into the interior of the liner string 14. Though shown relatively close together in the drawing, the two different producing zones and their respective liner perforations may actually be a considerable distance apart from one another. A permanent production packer 18 is set in the production liner 14 at a point intermediate the two producing zones 16 and 17.

Connected to the upper end of the liner hanger 15 is a tubular receptacle member 20 which constitutes one of the novel features of the present invention. The cement 13 extends up the annulus between the casing 12 and the receptacle member 20. Thus, receptacle member 20 and liner hanger 15 are cemented into place to form a permanent part of the completed well. Thus, the receptacle member 20 becomes a permanent part of the production liner string 14. The receptacle member 20 is provided with an outwardly extending flange 21 for purposes of limiting the upward flow of cement 13. In the alternative, a tieback receptacle may be connected to the upper end of the receptacle member 20.

The interior wall of the receptacle member 20 is machined and polished to a relatively smooth finish and a layer of insulation material is coated onto this polished surface. This insulation material is a plastic material whose exposed surface has good antisticking properties. Fluorocarbon plastic materials and, in particular, polytetrafluoroethylene and fluorinated ethylene-propylene have been found to be particularly suitable for this purpose. Both of these materials are sold under the DuPont trademark of Teflon, the former being identified as type TFE Teflon" and the letter type FEP Teflon." The thickness of this coating on the interior of receptacle member 20 is on the order of 0.002 inch. The length of the receptacle member 20 is in the range of from 6 inches to 6 feet, the preferred length for a particular situation being dependent on the depth at which the receptacle member 20 is to be located, the subsurface pressures and temperatures, and the like.

The completion apparatus further includes a dual flow seal assembly 22 which includes a cylindrical body member 23 adapted to be inserted into the receptacle member 20. The body member 23 includes a pair of flow passages 24 and 25 which extend longitudinally therethrough. Mounted on the exterior of the lower portion of the body member 23 is resilient annular seal means 26 for providing a fluidtight seal between the receptacle member 20 and the body member 23.

The flow passage 24 in the body member 23 is connected in a first string of removable production tubing at an intermediate point in such string. This first production tubing string 27 includes an upper tubing string portion 27a connected to the upper end of the flow passage 24 and extending upwardly to the wellhead equipment located at the surface of the earth. Tubing string 27 further includes a lower tubing string portion 27b connected to the lower end of the flow passage 24 and extending downwardly through the permanent production packer 18 to the lower producing zone 17. A series of production seal nipples 27c is connected in series in the lower tubing string portion 27b for cooperating with the packer 18 for providing a fluidtight seal which isolates the lower producing zone 17 from the upper zone 16. The flow passage 24 and tubing string 27 enable the formation fluid from the lower zone 17 to be carried to the wellhead equipment located at the surface of the earth.

The second flow passage in the body member 23 is adapted to receive the lower end of a second string of removable production tubing 28 which extends upwardly to the wellhead equipment located at the surface of the earth. A stinger sub 28a is connected to the lower end of the tubing string 28 for purposes of making the connection with the flow passage 25. Such sub 28a includes an annular seal 28b for providing a fluidtight seal with the wall of the flow passage 25. The flow passage 25, together with the tubing string 28, enables the formation fluid from the upper zone 16 to be carried to the wellhead equipment located at the surface of the earth.

- Referring now to FIG. 2, there is shown an enlarged crosssectional view of the dual flow seal assembly 22. As there shown, the upper end of the body member 23 is cut at an oblique angle to provide an inclined trough 30 for guiding the stinger sub 28a into the flow passage 25. The upper end of the flow passage 25 is provided with an enlarged receptacle portion 31 for receiving the stinger sub 28a. Grooves 32 and 33 are formed in the inner wall of the passage 25 at points below the receptacle portion 31 for purposes of latching therein a closure plug in the event it should become desirable to close off the upper producing zone 16.

The flow passage 24 for the lower zone tubing string includes threaded portions 34 and 35 formed in the wall of such flow passage 24 at the two ends thereof for connecting the two ends of such passage 24 to the threaded ends of the upper and lower portions 27a and 27b ofthe tubing string 27.

The lower portion of the body member 23 is of reduced outside diameter relative to the upper portion of such body member. This provides an intermediate exterior shoulder 37 for engaging the upper flange 21 of the receptacle member 20 for limiting the extent to which the body member 23 is inserted into such receptacle member 20. The outside diameter of the body member 23 above the shoulder 37 is appreciably greater than the inside diameter of the receptacle member 20, while the outside diameter of the body member 23 below the shoulder 37 is somewhat less than the inside diameter of such receptacle member 20 including the layer ofinsulation materi al coated on the interior thereof. As a consequence, a few hundredths or, in some cases, a few thousandths of an inch of clearance is provided between the lower portion of the body member 23 and the surface of the insulation material coated on the interior of the receptacle member 20. The longitudinal location of the shoulder 37 is such that the lower end of the body member 23, including a retainer ring 38 threaded onto the lower end thereof, will not quite reach the bottom end of the receptacle member 20.

The annular seal means 26 mounted on the body member 23 near the lower end thereof includes a plurality of annular seal rings 40 stacked against one another and a pair of adapter rings 41 and 42 positioned against the seal rings at the two ends of the stack. Each of these seal rings 40 is constructed to have an approximately chevron-shaped cross section. As indicated in the drawing, the upper ones of the seal rings 40 are oriented to point in an upwardly direction, while the lower ones are oriented to point in a downwardly direction. In this case, an additional adapter ring 43 is located intermediate the upwardly and downwardly pointing sets.

The complete stack formed by seal rings 40 and adapter rings 41-43 is mounted in an annular recess 44 formed on the exterior of the lower portion of the body member 23. This recess 44 is formed by a reduced-diameter portion 45 of the body member 23 and the internally threaded retainer ring 38 which is threaded onto the externally threaded lower end of the reduced-diameter portion 45. The seal rings 40 and adapter rings 41-43 are slipped over the lower end of the body member 23 with the retainer ring 38 removed. The retainer ring 38 is then screwed into place so that the upper adapter ring 41 is in firm engagement with the shoulder 46 at the upper end of the recess 44 and the lower adapter ring 42 is in firm engagement with the upper surface 47 of the retainer ring 38.

As is indicated in the drawing, the overall outside diameter of the seal rings 40 is such that these seal rings extend laterally out of or beyond the lip of the recess 44. In addition, this overall outside diameter for the seal rings 40 is somewhat greater than the inside diameter of the receptacle member 20 into which the body member 23 is to be inserted. In this regard, the seal rings 40 are constructed ofa resilient insulation material having sufficient resilience to enable sufficient compression thereof to allow passage of the seal rings 40 into the receptacle member 20. At the same time, the resilient forces produced by this compression provide an extremely tight fluid seal with the interior wall of the receptacle member 20. A material which has been found to be particularly suitable for the seal rings 40 is a composition material comprising a mixture of fluoroelastomer material and asbestos. One form of this material is sold under the DuPont trademark of"Viton." The adapter rings 41-43, on the other hand, may be formed of a fluorocarbon plastic material such as either polytetrafluoroethylene or fluorinated ethylene-propylene.

The length of the recess 44 and the number of seal rings 40 can be varied to meet the subsurface conditions to be encountered in the particular well bore in which the apparatus is to be used. In particular, the longitudinal length of the seal ring stack, like the length of the receptacle member 20, can vary over a range of 6 inches to 6 feet. In other words, where subsurface conditions require it, the lower end of the body member 23 can be made of a greater length and a longer recess 44 provided thereon for holding a larger number of seal rings 40.

Other types of seal rings may be used in place of the chevron-type rings 40. For example, seal rings having either a rectangular cross section or a W-shaped cross section may instead be used. Also, in some cases, it will be desired to have the individual seal rings spaced apart from another. In such cases, appropriate spacer rings are located intermediate the seal rings.

In the initial setup of the apparatus shown in FIG. 1, the seal assembly 22, including the body member 23 and seal means 26, is connected at the appropriate intermediate point in the tubing string 27 for the lower producing zone 17. This tubing string 27 is then run into the well bore casing 12 until the shoulder 37 on the body member 23 seats on the top flange 21 of the receptacle member 20. The second tubing string 28 for the upper producing zone 16 is then run into the borehole casing 12 and the stinger sub 28a seated in the enlarged receptacle 31 at the upper end of the body member 23. The upper ends of the two tubing strings 27 and 28 are then secured to the wellhead equipment located at the surface of the earth. The well is then ready for the performance of any remaining operations that may be required preparatory to commencing production from the two subsurface earth zones.

In order to reenter the upper portion of the production liner 14 at a later date for workover purposes and the like, it is only necessary to withdraw the upper zone tubing string 28 and then to withdraw the lower zone tubing string 27 including the seal assembly 22. In this regard, it is noted that the inside diameter of the receptacle member 20 is at least as large as the minimum inside diameter of the remainder of the production liner string 14. As a consequence, the receptacle member 20 in no way restricts the passage of a workover tool or other device which is otherwise capable of passing into the produc tion liner string 14.

Another point to note is the fact that the lower portion of the body member 23 is constructed to avoid the possibility of a metal-to-metal contact between such body member 23 and the inner wall of the receptacle member 20. This, together with the presence of the insulation material on the inner wall of the receptacle member 20, considerably minimizes the occurrence of electrolysis effects and the like which would otherwise tend to stick the body member 23 in the receptacle 20.

It should be further noted that the completion apparatus shown in FIG. 1 does not require the setting of a production packer at the lower end of the upper zone tubing string. In addition to simplifying the completion equipment and procedure, this also considerably facilitates any later reentry into the production liner.

While there have been described what are at present considered to be preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, intended to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. Apparatus for use in completing oil and gas wells for producing from a plurality of subsurface zones comprising:

a tubular receptacle member adapted to be permanently connected into a string of permanent production liner;

a cylindrical body member adapted to be inserted into the receptacle member and having a plurality of flow passages extending longitudinally therethrough;

and resilient annular seal means mounted on the exterior of the body member for contacting said tubular receptacle member and forming a seal between said receptacle member and the exterior of said body member while accommodating relative longitudinal movement between said cylindrical body and said receptacle member.

2. Apparatus in accordance with claim 1 wherein the interior wall surface of the tubular receptacle member is coated.

3. Apparatus in accordance with claim 2 wherein the coating on the interior wall of the receptacle member is Teflon.

4. Apparatus in accordance with claim 11 wherein the annular seal means includes a plurality of seal rings stacked against one another.

5. Apparatus in accordance with claim 1 wherein a first of the flow passages is adapted to be connected in a first string of production tubing at an intermediate point in such string and a second of the flow passages is adapted to receive the lower end of a string of production tubing.

6. Apparatus for producing hydrocarbons from two different zones in a borehole drilled into the earth comprising:

a permanent production liner adapted to be cemented into place in the borehole;

a tubular receptacle member connected to the production liner at a point above the two producing zones and adapted to be cemented into place in the borehole;

a production packer adapted to be set in the production liner at a point intermediate the two producing zones and having an internal bore therethrough;

a cylindrical body member adapted to be inserted into said receptacle member and having a pair of flow passages extending longitudinally therethrough and having a lower portion adapted to be positioned within the receptacle member;

resilient annular seal means mounted on the exterior of said cylindrical body member for contacting said tubular receptacle member and forming a seal between said receptacle member and the exterior of said body member while accommodating relative longitudinal movement between said cylindrical body member and said receptacle member;

a tubing for connection with the lower end of said cylindrical body member to communicate with one of said pair of flow passages in said body member;

said tubing adapted to extend downwardly through the bore in said production packer;

said tubing having seal means thereon for engaging within the bore of said production packer to seal therewith while accommodating relative longitudinal movement between said tubing and production packer; and

said liner communicating with the other of said pair of flow passages in said cylindrical body member.

7. Apparatus in accordance with claim 6 including tubing for connection with said cylindrical body member to communicate said other of said pair of flow passages with the wellhead equipment located at the earth s surface.

8. Apparatus in accordance with claim 6 including tubing for connection with the upper end of said cylindrical member to communicate said one of said pair of flow passages with the wellhead equipment located at the earths surface.

9. Apparatus in accordance with claim 6 wherein the interior wall surface of the tubular receptacle member is coated with a layer of coating material. 

1. Apparatus for use in completing oil and gas wells for producing from a plurality of subsurface zones comprising: a tubular receptacle member adapted to be permanently connected into a string of permanent production liner; a cylindrical body member adapted to be inserted into the receptacle member and having a plurality of flow passages extending longitudinally therethrough; and resilient annular seal means mounted on the exterior of the body member for contacting said tubular receptacle member and forming a seal between said receptacle member and the exterior of said body member while accommodating relative longitudinal movement between said cylindrical body and said receptacle member.
 2. Apparatus in accordance with claim 1 wherein the interior wall surface of the tubular receptacle member is coated.
 3. Apparatus in accordance with claim 2 wherein the coating on the interior wall of the receptacle member is Teflon.
 4. Apparatus in accordance with claim 1 wherein the annular seal means includes a plurality of seal rings stacked against one another.
 5. Apparatus in accordance with claim 1 wherein a first of thE flow passages is adapted to be connected in a first string of production tubing at an intermediate point in such string and a second of the flow passages is adapted to receive the lower end of a string of production tubing.
 6. Apparatus for producing hydrocarbons from two different zones in a borehole drilled into the earth comprising: a permanent production liner adapted to be cemented into place in the borehole; a tubular receptacle member connected to the production liner at a point above the two producing zones and adapted to be cemented into place in the borehole; a production packer adapted to be set in the production liner at a point intermediate the two producing zones and having an internal bore therethrough; a cylindrical body member adapted to be inserted into said receptacle member and having a pair of flow passages extending longitudinally therethrough and having a lower portion adapted to be positioned within the receptacle member; resilient annular seal means mounted on the exterior of said cylindrical body member for contacting said tubular receptacle member and forming a seal between said receptacle member and the exterior of said body member while accommodating relative longitudinal movement between said cylindrical body member and said receptacle member; a tubing for connection with the lower end of said cylindrical body member to communicate with one of said pair of flow passages in said body member; said tubing adapted to extend downwardly through the bore in said production packer; said tubing having seal means thereon for engaging within the bore of said production packer to seal therewith while accommodating relative longitudinal movement between said tubing and production packer; and said liner communicating with the other of said pair of flow passages in said cylindrical body member.
 7. Apparatus in accordance with claim 6 including tubing for connection with said cylindrical body member to communicate said other of said pair of flow passages with the wellhead equipment located at the earth''s surface.
 8. Apparatus in accordance with claim 6 including tubing for connection with the upper end of said cylindrical member to communicate said one of said pair of flow passages with the wellhead equipment located at the earth''s surface.
 9. Apparatus in accordance with claim 6 wherein the interior wall surface of the tubular receptacle member is coated with a layer of coating material. 